Headphone systems are used in numerous environments and for various purposes, examples of which include entertainment purposes such as gaming or listening to music, productive purposes such as phone calls, and professional purposes such as aviation communications or sound studio monitoring, to name a few. Different environments and purposes may have different requirements for fidelity, noise isolation, noise reduction, voice pick-up, and the like. In some environments or in some applications it may be desirable to detect when the user of the headphones or headset is actively speaking.